1. Field of the Invention
This invention is concerned with lasers, and devices and optical systems that contain lasers. It is especially, but not exclusively, concerned with continuous wave lasers, for example continuous wave Raman lasers.
2. Discussion of Prior Art
It is known to produce laser light by pumping a single, large, laser crystal with light of an appropriate wavelength. Solid state Raman lasers are known, again using a large single crystal of Raman laser material. It is known to propose optical fibres made out of glass which when there are kilometres of fibre produce Raman laser light (when optically pumped).